74 BRITISH BIRDS. 



This subject is surrounded by difficult questions — difficult to every 

 biologist who is true to scientific method ; and I cannot hope, even with 

 twenty-five years' experience of my own and the aid of that of other 

 persons, to afford even an approximative solution which will secure a general 

 consensus of opinion on this recondite subject — one not unknown to Jeremiah 

 (viii. 7), and by the Romans held in superstitious awe. Still something may 

 be said, some light thrown upon it. Would that we had the books of the 

 College of Augurs to search, from the time of Romulus downwards — a college 

 chiefly devoted to the observance of birds and migration ; or even if we could 

 cross-examine the " magister," he could tell curious facts. It was Berryer 

 who stated that the Roman augurs could not look each other in the face 

 without laughing (Hayward's ' Critical Essays,' n. s. p. 394). Allowing 

 this to be the fact, it was because they were acute individuals and above the 

 superstition of the vulgus, having had their intellects sharpened by the study 

 of ornithology, and because they were so frequently obliged to defend their 

 false and fallacious raison d'etre ! 



I imagine the following are some of the heads of inquiry : — 



1 . Why do birds migrate ? From what cause .'' 



2. What makes the first bird move ? 



3. How do they find their way ? 



4. Where do they migrate to ? 



5. Why do they return, in defiance of the principle in Nature of 



least action ? 

 When considering these questions, I hope, instead of receiving only a 

 supercilious negation, to obtain a fair hearing of the facts. 



1 . Why do birds migrate ? 



To this question we might add, why do fish migrate — herrings, for 



instance, &c. ? and how do they find their way in the pathless ocean .'' It 



may be divided into others, thus :— Is it hunger and thirst ? is it cold or 



heat ? is it avriaropyr) in an ordinary season, or excessive multiplication in an 



